Japp, this is normal for small VMs and no changes due to some hot add mode specifics, and also because of your storage speed. If you had fibre channel SAN, and real VM workload with significant amount of changes, the results would be different

I too have the issue with slow performance when using Hot Add for replication and an error in vCenter "The requested operation is not implemented by the server" when trying to create a disk when the replication starts. I see the source datastore has been attached to Veeam VM, but what is perplexing to me is the Veeam VM's nic is running at 15000 KBps... ???

I was able to P2V the server in an hour and a half, over a 1Gbps connection, surely the initial replication shouldn't take 8 hours, should it? I've tested the disks inside the VM and see that I'm able to get 150 MBps sustained throughput, when tested on the SAN.